Millions of frogs are shifted around the world each year for sale as pets and food. Now research shows, for the first time, that this global trade is spreading two severe diseases – one of which is blamed for driving amphibians towards extinction.

Last year the World Organisation for Animal Health (OIE) took a step towards monitoring both diseases by making them "notifiable", but as yet there are no regulations to prevent the trade of infected frogs.

"This is a major issue," says Peter Daszak, president of the Wildlife Trust, and an expert on amphibian diseases. "Over a million bullfrogs a year come into the USA for food. If only five per cent are infected, that's 50,000 infected animals."